iPhone 5 wifi problem please help!

Ok guys I am currently at my wits end with my iPhone 5 on iOS 7.1.2.

My issue is that for my wifi to work I have to be within 10 of any router i try to connect to otherwise I can't get a connection, despite the wifi indicator having full bars or two.

I'm pretty sure I have tried every solution I can think of. Reseting network settings, reseting router, hard reset of iPhone, restoring to new iPhone.

Also as my warranty has been expired for over a year I thought to hell with it and replaced the wifi antenna cable inside the iPhone. That's 2 hours of my life I will never get back because that didn't work either!

I'm due for an upgrade and will be getting the iPhone 6 when it's released, however I'm desperate to fix my 5 so I don't have to sell it as having faulty wifi.

It's so frustrating considering my iPad Air running on 7.1.2 will work anywhere in the house, but the 5 only when I'm within 10 feet of the router.

If any of you know what's going on, or have a potential fix, I'd greatly appreciate it. The only thing I haven't tried is the freezer trick, and I'm getting tempted.

 

Thanks for your reply. I couldn't say a definite date but around the time 7.1 or 7.1.1 were released to March/April.

No Mods/jailbreaks the iPhone just runs standard iOS.

Both my iPad and iPhone are on the same home network, it's not just my home network where the problem occurs, when I go to my mums I have the same issue (needing to be within 10 feet of router with iPhone).